Next generation mobile communication systems have been standardized aiming at providing integrated services and effective interoperations between a wired communication network and a wireless communication network, beyond a simple wireless communication service provided in the conventional mobile communication systems. With the demand on a high-speed, large volume data communication system for processing and transmitting a variety of information such as radio data as well as providing voice-oriented services, there is a need for developing a technique for transmitting large-volume data through the wireless communication network whose capacity is similar to that of the wired communication network.
Hereinafter, a downlink denotes a communication link from a base station (BS) to a user equipment (UE), and an uplink denotes a communication link from the UE to the BS. A data channel denotes a channel for transmitting data. The data channel is classified into a downlink data channel and an uplink data channel. A control channel denotes a channel for transmitting a control signal. Scheduling information regarding the data channel is transmitted through the control channel. The scheduling information generally includes resource assignment information. The resource assignment information provides information regarding resources assigned to the downlink data channel and the uplink data channel.
The UE transmits uplink data through the uplink data channel. Thus, the UE has to receive uplink scheduling information from the BS before transmitting the uplink data. Likewise, the UE has to receive downlink scheduling information from the BS before receiving downlink data.
If an error occurs in the downlink control channel when the downlink scheduling information is transmitted thereon, the UE cannot successfully receive the downlink data since the downlink data channel cannot be known to the UE. In particular, when using a hybrid automatic repeat request (HARQ)-based system, the UE cannot feed back an acknowledgement (ACK)/negative-acknowledgement (NACK) signal. If the ACK/NACK signal cannot be fed back, the BS cannot know whether to transmit new data or to retransmit previous data, which may lead to deterioration in system performance. In addition, if an error occurs in the downlink control channel when the uplink scheduling information is transmitted thereon, the UE cannot transmit uplink data since the uplink data channel cannot be known to the UE.
As such, when the error occurs in the downlink control channel for transmitting scheduling information, the system may operate abnormally. In addition, if the error occurs in the control channel and a time for recovering the error is significantly delayed, a data rate may be decreased. Accordingly, there is a need for a data transfer method in which an error is handled according to a detected error pattern.